Advice against Tyranid Gargantuan Creatures

I have just lost a brill game against my regular opponent who runs a Tyranid horde. I was astonished to see a Barbed Hierodule placed down along with a Winged Tyrant and 2 Carnifex. I Killed the Tyrant and 1 'fex but the Hierodule took everything I through at it and proceded to cut down half my force. I was using 2 dev squads (hvy BG/PC & 4*LC),
2 tac cbt squads 2 ls T 1 assault squad 1 whirlwind and a Tech Marine + 4 hb servitors.
Any advice much appreciated.:cry:

In any case, wow. A flying Tyrant, twin 'Fexes, and a Hierodule?? Yikes!

Personally, I'd drop the Techmarine in favour of some sniper scouts. Between the HB/PC Devs and the Tacticals, you've got plenty of horde-thinning firepower handy, so you don't need the HB servitors so much.

Snipers give you plenty of easy wounds against the big beasties, you just need to wait for failed saves. Toss in a Missile launcher for a little AP3 goodness.

Try a Thunder Hammer on the Assault squad if they're gonna chase the big bugs - any wounds it causes force the bug to go at Initiative 1 next round... very handy.

My personal tactics prefer a Predator with HB sponsons over the Whirlwind - comparable firepower, just applied somewhat more directly. I also like a Librarian with a Jump pack to go in and try to Force Weapon the big bugs - it's worked wonderfully for me in the past.

They are only immune to instant death if they are under synapse.
A flying Tyrant will leave his slower moving buddies behind, so they can still be force weaponed to death. Still hard to even wound the buggers though..